1. FIELD OF THE INVENTION
The invention relates to a device for fixing a planar work piece in position, particularly a semiconductor used in processing cycles for the production of integrated circuits, said device having a supporting plane, a number of apertures being disposed in said supporting plane, said apertures being under reduced pressure, said work piece being pressed against said supporting plane by means of said reduced pressure.
2. DESCRIPTION OF THE PRIOR ART
It is known in the art to fix planar work pieces in position by means of reduced pressure. When producing integrated circuits, a semiconductor substrate must be fixed onto a bench during certain processing cycles, e.g. when transferring photomasks onto a photo-sensitive layer of the semiconductor substrate. For this purpose a number of apertures communicating with a reduced pressure generating device are disposed in the bench surface so that the lower side of the substrate is pressed against the supporting plane.
It is one problem of such prior art devices that the lower side of the plate-shaped semiconductor substrate can have raised areas, which prevent the required building up of the reduced pressure. In this case the substrate surface does not coincide with the supporting plane, which may cause faults in the processing cycles.
This disadvantage is of great importance as substrates of increasing diameters have been developed, which may consequently have an increasing number of warps and raised areas on their lower sides.
Attempts have already been made to press the substrate against the bench by electrostatic means instead of by reduced pressure. Electrostatic contact pressure involves technical difficulties and high cost.